(a) Field of the Invention
The present invention relates to a motor direct driven compressor system, and more particularly to a technology of driving an air-conditioning compressor of an automobile by an electric motor.
(b) Description of the Related Art
Automobile air-conditioning compressor is a key component of an automobile air-conditioning system, whose working environment and conditions are not as good as those of air conditioners in a building or at a home or other fixed air conditioners in the following aspects: 1. The change of thermal load outside the automobile is large, and since the automobile is a moving object, therefore the change of external whether conditions is large; 2. The required air-conditioning load is large, and thus a quick temperature drop is required; 3. The automobile is operated in an environment with vibrations and bumpy roads, and thus the automobile air-conditioning system requires the shock resistance and bumping resistance; 4. The automobile is exposed to direct sunlight most of the time, the thermal load at the driver seat and passenger seats is much larger than a room; 5. There is a large heat loss in the automobile, since it is difficult to insulate heat of an automobile; 6. A high-performance air-conditioner is required for the automobile.
In addition, most automobile air-conditioning compressors are driven by an engine of the automobile, but hybrid vehicles, electric cars and fuel cell cars are driven by an electric generator. Since the rotation speed of the compressor is affected by the rotation speed of the engine, there is a larger charge of rotation speed, varying from idle speed to maximum speed, and thus the automobile air-conditioning compressor requires the following: 1. Good low-speed performance is required, so that a high cooling performance can be provided for a low-speed operation. 2. Low input power is required for a high speed operation to save gas consumption and improve dynamic power. 3. Small volume and light weight. 4. High reliability is required for operations in poor weather conditions, and thus the compressor must be able to resist high temperature and high pressure, and components must be highly vibration resisting and sealed for a high-speed operation of a car on a bumpy road. 5. The operation of the compressor must be stable, steady, low vibrating and low noise, and thus the use of automobile air-conditioning compressor has much stricter limitations over compressors of other types.
At present, most automobiles adopt an internal combustion engine and petroleum (or diesel) as power source, and components including a belt, a belt pulley and the like for driving and turning on the air-conditioning compressor. As the issues of energy crisis and environmental protection become increasingly serious, the aforementioned hybrid vehicles, electric cars and fuel cell cars are introduced to the market. Although the hybrid vehicles use both petroleum and electric power as dual power source, and a petroleum engine is used for driving the air-conditioning compressor, and present technologies integrate the technology of the electric cars, yet the air pollution produced by the petroleum engine still has the air pollution issue, and thus hybrid vehicles are just transitional products only, and definitely required further improvements.
If the technology of home air-conditioning compressors is adopted to substitute the use of automobile air-conditioning compressors, it is very difficult to overcome the aforementioned problems of the strict using environment of the automobile air-conditioning compressor, and obviously the home air-conditioning compressors are not applicable in this case.
Therefore, it is an important subject for related researches and manufacturers to provide an appropriate way of driving an automobile air-conditioning compressor.